Developments in combinatorial chemistry have concentrated on the synthesis of chemical compounds. For example, U.S. Pat. No. 5,612,002 B1 and U.S. Pat. No. 5,766,556 B1 disclose a method and apparatus for multiple simultaneous synthesis of compounds. WO 97/30784-A1 discloses a microreactor for the synthesis of chemical compounds. Akporiaye, D. E.; Dahl, I. M.; Karlsson, A.; Wendelbo, R. Angew Chem. Int. Ed. 1998, 37, 609–611 disclose a combinatorial approach to the hydrothermal synthesis of zeolites, see also WO 98/36826. Other examples include U.S. Pat. No. 5,609,826, U.S. Pat. No. 5,792,431, U.S. Pat. No. 5,746,982, and U.S. Pat. No. 5,785,927, and WO 96/11878-A1.
More recently, combinatorial chemistry approaches have been applied to catalyst testing in an attempt to expedite the testing process. With the growing number of materials being synthesized combinatorially, more efficient methods of evaluating the materials are needed. Especially needed are combinatorial methods for the evaluation of solids that are designed to keep pace with the speed of combinatorial synthesis. For example, WO 97/32208-A1 teaches placing different catalysts in a multicell holder. The reaction occurring in each cell of the holder is measured to determine the activity of the catalysts by observing the heat liberated or absorbed by the respective formulation during the course of the reaction, and/or analyzing the products or reactants. Thermal imaging had been used as part of other combinatorial chemistry approaches to catalyst testing; see Holzwarth, A.; Schmidt, H.; Maier, W. F. Angew. Chem. Int. Ed., 1998, 37, 2644–2647, and Bein, T. Angew. Chem. Int. Ed., 1999, 38, 323–326. Thermal imaging may be a tool to gain knowledge of some semi-quantitative information regarding the activity of the catalyst, but it provides no indication as to the selectivity of the catalyst.
Some attempts to acquire information as to the reaction products in rapid-throughput catalyst testing are described in Senkam, S. M. Nature, July 1998, 384(23), 350–353, where laser-induced resonance-enhanced multiphoton ionization is used to analyze a gas flow from each of the fixed catalyst sites. Similarly, Cong, P.; Doolen, R. D.; Fan, Q.; Giaquinta, D. M.; Guan, S.; McFarland, E. W.; Poojary, D. M.; Self, K.; Turner, H. W.; Weinberg, W. H. Angew Chem. Int. Ed. 1999, 38, 484–488 teaches using a probe with concentric tubing for gas delivery/removal and sampling. Only the fixed bed of catalyst being tested is exposed to the reactant stream, with the excess reactants being removed via vacuum. The single fixed bed of catalyst being tested is heated and the gas mixture directly above the catalyst is sampled and sent to a mass spectrometer.
Combinatorial chemistry has been applied to evaluate the activity of catalysts. Some applications have focused on determining the relative activity of catalysts in a library; see Klien, J.; Lehmann, C. W.; Schmidt, H.; Maier, W. F. Angew Chem. Int. Ed. 1998, 37, 3369–3372; Taylor, S. J.; Morken, J. P. Science, April 1998, 280(10), 267–270; and WO 99/34206-A1. Some applications have broadened the information sought to include the selectivity of catalysts. WO 99/19724-A1 discloses screening for activities and selectivities of catalyst libraries having addressable test sites by contacting potential catalysts at the test sites with reactant streams forming product plumes. The product plumes are screened by passing a radiation beam of an energy level to promote photoions and photoelectrons, which are detected by microelectrode collection. WO 98/07026-A1 discloses miniaturized reactors where the effluent is analyzed during the reaction time using spectroscopic analysis.
Some commercial processes have operated using multiple parallel reactors where the products of all of the reactors are combined into a single product stream; see U.S. Pat. No. 5,304,354 and U.S. Pat. No. 5,489,726. Another patent, U.S. Pat. No. 6,149,882 B1 teaches an apparatus having a plurality of vessels and valves and conduits for sequentially sampling the effluent of the vessels or a sample probe positioned next to the effluent to transport sampled fluid to a detector.
Applicants have developed a combinatorial method and apparatus particularly suited for the generation of a plurality of independent effluents. The effluents are generated in parallel, but kept isolated from one another. The effluent may be further processed by, for example, analyzing the composition of the effluent, by further reacting the effluent, by further treating the effluent, and the like. One embodiment of the invention is the evaluation of a plurality of solids where the effluents of all the vessels are simultaneously sampled. Another embodiment of the invention is the evaluation of a plurality of solids where the effluents of all the vessels are sequentially sampled. Multiple solids are contacted with a feed fluid in parallel with the resulting effluents being sampled, simultaneously or sequentially, and then analyzed for changes as compared to the feed fluid. The parallel reactions and the analyses provide a means for the high throughput evaluation of multiple solids or mixtures of solids.